Embodiments of the present invention relates to a method for detecting a pattern offset amount of exposed regions and a detecting mark.
Thin film transistor liquid crystal displays (TFT-LCDs) have the advantages of small volume, low power consumption, low radiation and the like, and thus have predominated in the current flat plate display market.
A TFT-LCD is formed by bonding an array substrate and a color filter substrate together. On the array substrate, gate lines and signal lines are formed to intersect with one another so as to define pixel regions, and a pixel electrode and a thin film transistor are arranged in each pixel region.
In the current manufacturing processes of a TFT-LCD, the different regions in the same structure layer sometimes need to be respectively exposed, and at this time, a pattern offset amount of exposed regions in the same structure layer need to be detected so as to ensure the uniform arrangement of patterns of the exposed regions.
In one detecting or testing process as shown in FIG. 1, when a first region 1 is exposed, besides photoresist patterns for a array structure are formed, a sets of photoresist patterns 2 not exposed are simultaneously formed for detecting marks in the periphery of the first region 1, and shape of the photoresist patterns 2 may be a rectangle, a circle and the like (as shown in FIG. 1(a)). Then, when a second region 3 is exposed in the same layer, besides that photoresist patterns for the array structure are formed in the second region 3, the patterns 2 formed in the previous exposure process are again exposed so as to form photoresist patterns 4 subject to exposure and each slightly smaller than patterns 2 (as shown in FIG. 1(b)). When a pattern offset amount between the two exposing processes is in a specified range, the patterns 4 are located inside of the patterns 2, and after the photoresist is developed, the patterns 4 and 2 form ring shape structures. Pattern offset amounts at the upper portion, the lower portion, the left portion and the right portion of each ring shape structure can be respectively detected by a microscope, a camera, an image processing device and the like, and thus, the pattern offset amount can be determined.
However, it takes long time to detect the pattern offset amount of exposed regions in the above process, and thus a full detection of a glass substrate is difficult to be achieved, a missing detection easily occurs, and a defective product may unintentionally enter subsequent processes.